Method and apparatus for distinguishing transmission feedback mode in sidelink buffer status report in a wireless communication system

ABSTRACT

A method and apparatus are disclosed from the perspective of a UE (User Equipment) to handle a sidelink buffer status report (SL BSR). In one embodiment, the method includes the UE transmitting a SL BSR to a network node, wherein a format of the SL BSR includes at least one field of buffer size associated with HARQ (Hybrid Automatic Repeat Request) feedback enabled and one field of buffer size associated with HARQ feedback disabled. The method also includes the UE receiving a sidelink grant from the network node. The method further includes the UE selecting data from a logical channel for transmission according to a HARQ feedback mode of the logical channel and whether the sidelink grant is associated with a HARQ feedback resource or not.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. Provisional PatentApplication Ser. No. 62/849,422 filed on May 17, 2019, the entiredisclosure of which is incorporated herein in its entirety by reference.

FIELD

This disclosure generally relates to wireless communication networks,and more particularly, to a method and apparatus for distinguishingtransmission feedback mode in sidelink buffer status report in awireless communication system.

BACKGROUND

With the rapid rise in demand for communication of large amounts of datato and from mobile communication devices, traditional mobile voicecommunication networks are evolving into networks that communicate withInternet Protocol (IP) data packets. Such IP data packet communicationcan provide users of mobile communication devices with voice over IP,multimedia, multicast and on-demand communication services.

An exemplary network structure is an Evolved Universal Terrestrial RadioAccess Network (E-UTRAN). The E-UTRAN system can provide high datathroughput in order to realize the above-noted voice over IP andmultimedia services. A new radio technology for the next generation(e.g., 5G) is currently being discussed by the 3GPP standardsorganization. Accordingly, changes to the current body of 3GPP standardare currently being submitted and considered to evolve and finalize the3GPP standard.

SUMMARY

A method and apparatus are disclosed from the perspective of a UE (UserEquipment) to handle a sidelink buffer status report (SL BSR). In oneembodiment, the method includes the UE transmitting a SL BSR to anetwork node, wherein a format of the SL BSR includes at least one fieldof buffer size associated with HARQ (Hybrid Automatic Repeat Request)feedback enabled and one field of buffer size associated with HARQfeedback disabled. The method also includes the UE receiving a sidelinkgrant from the network node. The method further includes the UEselecting data from a logical channel for transmission according to aHARQ feedback mode of the logical channel and whether the sidelink grantis associated with a HARQ feedback resource or not.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a diagram of a wireless communication system according toone exemplary embodiment.

FIG. 2 is a block diagram of a transmitter system (also known as accessnetwork) and a receiver system (also known as user equipment or UE)according to one exemplary embodiment.

FIG. 3 is a functional block diagram of a communication system accordingto one exemplary embodiment.

FIG. 4 is a functional block diagram of the program code of FIG. 3according to one exemplary embodiment.

FIG. 5 is a reproduction of Figure A-1 of 3GPP R2-1900370.

FIG. 6 is a reproduction of Figure A-2 of 3GPP R2-1900370.

FIG. 7 is a reproduction of FIG. 6.1.3.1a-1 of 3GPP TS 36.321 V15.3.0.

FIG. 8 is a reproduction of FIG. 6.1.3.1a-2 of 3GPP TS 36.321 V15.3.0.

FIG. 9 is a reproduction of Table 6.2.1-1 of 3GPP TS 36.321 V15.3.0.

FIG. 10 is a reproduction of Table 6.2.1-1a of 3GPP TS 36.321 V15.3.0.

FIG. 11 is a reproduction of Table 6.2.1-2 of 3GPP TS 36.321 V15.3.0.

FIG. 12 is a reproduction of FIG. 6.1.2-1 of 3GPP TS 38.321 V15.5.0.

FIG. 13 is a reproduction of FIG. 6.1.2-2 of 3GPP TS 38.321 V15.5.0.

FIG. 14 is a reproduction of FIG. 6.1.2-3 of 3GPP TS 38.321 V15.5.0.

FIG. 15 is a reproduction of FIG. 6.1.2-4 of 3GPP TS 38.321 V15.5.0.

FIG. 16 is a reproduction of FIG. 6.1.2-5 of 3GPP TS 38.321 V15.5.0.

FIG. 17 is a reproduction of Table 6.2.1-1 of 3GPP TS 38.321 V15.5.0.

FIG. 18 is a reproduction of Table 6.2.1-2 of 3GPP TS 38.321 V15.5.0.

FIGS. 19A and 19B are examples of a SL BSR format according to oneexemplary embodiment.

FIG. 20 is an example of a SL BSR format according to one exemplaryembodiment.

FIG. 21 is an example of a LCID (Logical Channel Identity) usage for SLBSR format according to one exemplary embodiment.

FIG. 22 is an example of a MAC (Medium Access Control) subheader formatfor SL BSR according to one exemplary embodiment.

FIG. 23 is a flow chart according to one exemplary embodiment.

FIG. 24 is a flow chart according to one exemplary embodiment.

FIG. 25 is a flow chart according to one exemplary embodiment.

FIG. 26 is a flow chart according to one exemplary embodiment.

FIG. 27 is a flow chart according to one exemplary embodiment.

DETAILED DESCRIPTION

The exemplary wireless communication systems and devices described belowemploy a wireless communication system, supporting a broadcast service.Wireless communication systems are widely deployed to provide varioustypes of communication such as voice, data, and so on. These systems maybe based on code division multiple access (CDMA), time division multipleaccess (TDMA), orthogonal frequency division multiple access (OFDMA),3GPP LTE (Long Term Evolution) wireless access, 3GPP LTE-A orLTE-Advanced (Long Term Evolution Advanced), 3GPP2 UMB (Ultra MobileBroadband), WiMax, 3GPP NR (New Radio), or some other modulationtechniques.

In particular, the exemplary wireless communication systems devicesdescribed below may be designed to support one or more standards such asthe standard offered by a consortium named “3rd Generation PartnershipProject” referred to herein as 3GPP, including: TS 36.321 V15.3.0,“Evolved Universal Terrestrial Radio Access (E-UTRA); Medium AccessControl (MAC) protocol specification”; R2-1900370, “Summary of EmailDiscussion [104 #58][NR V2X]—QoS support for NR V2X”; 3GPP RAN1 #95Chairman's note; and TS 38.321 V15.5.0, “NR; Medium Access Control (MAC)protocol specification”. The standards and documents listed above arehereby expressly incorporated by reference in their entirety.

FIG. 1 shows a multiple access wireless communication system accordingto one embodiment of the invention. An access network 100 (AN) includesmultiple antenna groups, one including 104 and 106, another including108 and 110, and an additional including 112 and 114. In FIG. 1, onlytwo antennas are shown for each antenna group, however, more or fewerantennas may be utilized for each antenna group. Access terminal 116(AT) is in communication with antennas 112 and 114, where antennas 112and 114 transmit information to access terminal 116 over forward link120 and receive information from access terminal 116 over reverse link118. Access terminal (AT) 122 is in communication with antennas 106 and108, where antennas 106 and 108 transmit information to access terminal(AT) 122 over forward link 126 and receive information from accessterminal (AT) 122 over reverse link 124. In a FDD system, communicationlinks 118, 120, 124 and 126 may use different frequency forcommunication. For example, forward link 120 may use a differentfrequency then that used by reverse link 118.

Each group of antennas and/or the area in which they are designed tocommunicate is often referred to as a sector of the access network. Inthe embodiment, antenna groups each are designed to communicate toaccess terminals in a sector of the areas covered by access network 100.

In communication over forward links 120 and 126, the transmittingantennas of access network 100 may utilize beamforming in order toimprove the signal-to-noise ratio of forward links for the differentaccess terminals 116 and 122. Also, an access network using beamformingto transmit to access terminals scattered randomly through its coveragecauses less interference to access terminals in neighboring cells thanan access network transmitting through a single antenna to all itsaccess terminals.

An access network (AN) may be a fixed station or base station used forcommunicating with the terminals and may also be referred to as anaccess point, a Node B, a base station, an enhanced base station, anevolved Node B (eNB), or some other terminology. An access terminal (AT)may also be called user equipment (UE), a wireless communication device,terminal, access terminal or some other terminology.

FIG. 2 is a simplified block diagram of an embodiment of a transmittersystem 210 (also known as the access network) and a receiver system 250(also known as access terminal (AT) or user equipment (UE)) in a MIMOsystem 200. At the transmitter system 210, traffic data for a number ofdata streams is provided from a data source 212 to a transmit (TX) dataprocessor 214.

In one embodiment, each data stream is transmitted over a respectivetransmit antenna. TX data processor 214 formats, codes, and interleavesthe traffic data for each data stream based on a particular codingscheme selected for that data stream to provide coded data.

The coded data for each data stream may be multiplexed with pilot datausing OFDM techniques. The pilot data is typically a known data patternthat is processed in a known manner and may be used at the receiversystem to estimate the channel response. The multiplexed pilot and codeddata for each data stream is then modulated (i.e., symbol mapped) basedon a particular modulation scheme (e.g., BPSK, QPSK, M-PSK, or M-QAM)selected for that data stream to provide modulation symbols. The datarate, coding, and modulation for each data stream may be determined byinstructions performed by processor 230.

The modulation symbols for all data streams are then provided to a TXMIMO processor 220, which may further process the modulation symbols(e.g., for OFDM). TX MIMO processor 220 then provides N_(T) modulationsymbol streams to N_(T) transmitters (TMTR) 222 a through 222 t. Incertain embodiments, TX MIMO processor 220 applies beamforming weightsto the symbols of the data streams and to the antenna from which thesymbol is being transmitted.

Each transmitter 222 receives and processes a respective symbol streamto provide one or more analog signals, and further conditions (e.g.,amplifies, filters, and upconverts) the analog signals to provide amodulated signal suitable for transmission over the MIMO channel. N_(T)modulated signals from transmitters 222 a through 222 t are thentransmitted from N_(T) antennas 224 a through 224 t, respectively.

At receiver system 250, the transmitted modulated signals are receivedby N_(R) antennas 252 a through 252 r and the received signal from eachantenna 252 is provided to a respective receiver (RCVR) 254 a through254 r. Each receiver 254 conditions (e.g., filters, amplifies, anddownconverts) a respective received signal, digitizes the conditionedsignal to provide samples, and further processes the samples to providea corresponding “received” symbol stream.

An RX data processor 260 then receives and processes the N_(R) receivedsymbol streams from N_(R) receivers 254 based on a particular receiverprocessing technique to provide N_(T) “detected” symbol streams. The RXdata processor 260 then demodulates, deinterleaves, and decodes eachdetected symbol stream to recover the traffic data for the data stream.The processing by RX data processor 260 is complementary to thatperformed by TX MIMO processor 220 and TX data processor 214 attransmitter system 210.

A processor 270 periodically determines which pre-coding matrix to use(discussed below). Processor 270 formulates a reverse link messagecomprising a matrix index portion and a rank value portion.

The reverse link message may comprise various types of informationregarding the communication link and/or the received data stream. Thereverse link message is then processed by a TX data processor 238, whichalso receives traffic data for a number of data streams from a datasource 236, modulated by a modulator 280, conditioned by transmitters254 a through 254 r, and transmitted back to transmitter system 210.

At transmitter system 210, the modulated signals from receiver system250 are received by antennas 224, conditioned by receivers 222,demodulated by a demodulator 240, and processed by a RX data processor242 to extract the reserve link message transmitted by the receiversystem 250. Processor 230 then determines which pre-coding matrix to usefor determining the beamforming weights then processes the extractedmessage.

Turning to FIG. 3, this figure shows an alternative simplifiedfunctional block diagram of a communication device according to oneembodiment of the invention. As shown in FIG. 3, the communicationdevice 300 in a wireless communication system can be utilized forrealizing the UEs (or ATs) 116 and 122 in FIG. 1 or the base station (orAN) 100 in FIG. 1, and the wireless communications system is preferablythe LTE or NR system. The communication device 300 may include an inputdevice 302, an output device 304, a control circuit 306, a centralprocessing unit (CPU) 308, a memory 310, a program code 312, and atransceiver 314. The control circuit 306 executes the program code 312in the memory 310 through the CPU 308, thereby controlling an operationof the communications device 300. The communications device 300 canreceive signals input by a user through the input device 302, such as akeyboard or keypad, and can output images and sounds through the outputdevice 304, such as a monitor or speakers. The transceiver 314 is usedto receive and transmit wireless signals, delivering received signals tothe control circuit 306, and outputting signals generated by the controlcircuit 306 wirelessly. The communication device 300 in a wirelesscommunication system can also be utilized for realizing the AN 100 inFIG. 1.

FIG. 4 is a simplified block diagram of the program code 312 shown inFIG. 3 in accordance with one embodiment of the invention. In thisembodiment, the program code 312 includes an application layer 400, aLayer 3 portion 402, and a Layer 2 portion 404, and is coupled to aLayer 1 portion 406. The Layer 3 portion 402 generally performs radioresource control. The Layer 2 portion 404 generally performs linkcontrol. The Layer 1 portion 406 generally performs physicalconnections.

The appendix in 3GPP R2-1900370 described several candidate options forNW configured or pre-configured SLRB as follows:

Appendix: Candidate Options for NW Configured/Pre-Configured SLRB

As per experience from LTE SL, UEs with different RRC states/resourceallocation modes may depend on different ways of signaling andprocedures for their SL (pre-)configuration (i.e. dedicated signaling,system information and pre-configuration). Therefore, options withdifferent signaling flows are given below.

Option 1

Figure A-1 of 3GPP R2-1900370, entitled “PC5 QoS profile based, UEspecific configuration”, is reproduced as FIG. 5Since SA2 concluded to define VQI to represent the per-packet PC5 QoSparameters in TR 23.786 and indicates that the VQI of each V2X message(whenever applicable) is set by application layer [1], this option isbased on such conclusions and further assumes that the PC5 QoSparameters (e.g. VQI, etc.¹), namely PC5 QoS profiles², tagged on eachV2X packet is also submitted to the AS (similar to legacy PPPP/PPPR) asin Step 2 above. In Step 3, the UE may report the PC5 QoS profiles ofthe packet(s) to the gNB/ng-eNB, and requests the configuration of theSLRB(s) associated with these PC5 QoS profile(s) reported. As aresponse, the gNB/ng-eNB may signal the configurations of the SLRB(s)associated with the PC5 QoS profile(s) reported; these SLRBconfigurations may include SLRB ID, PC5 QoS profile to SLRB mapping,SDAP/PDCP/RLC/LCH configurations, etc. In Step 5, the UE in the ASestablishes SLRB(s) associated with the QoS profile of the packet(s) asper gNB/nb-eNB configuration, and maps the packet(s) to the SLRB(s)established. Afterward, SL transmission happens. ¹ Here, the specificPC5 QoS parameters in the figure include VQI and other potential QoSparameters identified by Q2, so that the “etc.” placed here might beupdated as per Q2 conclusion later (if the option itself is finallysupported). This applies also to Option 3 &4 below² Similar to Uu, theterm “PC5 QoS profile” here means a set of PC5 QoS parameters, i.e. VQIand other potential QoS parameters from Q2.Since SA2 assume that “non-standardized VQI is not supported in thisrelease” in TR 23.786 [1], it is quite likely that, similar to 5QI usedin NR Uu, the PC5 QoS parameters of each VQI are also standardized inthe specification. Also, if VQI itself is regarded as not sufficient toreflect all PC5 QoS parameters in Q2, other necessary QoS parameterswill be used together with VQI to form the PC5 QoS profile and reportedto the RAN as well. Therefore, this option is characterized by enablingthe UE to directly “tell” the QoS parameters of available packets in RANto the gNB/ng-eNB which thus no longer needs to rely on CN to get awareof the QoS profiles of the UE's traffic as in Uu.

Applicability:

In this option, the gNB/ng-eNB configures SLRB depending on the PC5 QoSparameters of the actually packets available as reported by the UE, soit works in a UE-specific manner and is applied to RRC_CONNECTED UEs.

Option 2

Figure A-2 of 3GPP R2-1900370, entitled “PC5 QoS flow based, UE specificconfiguration”, is reproduced as FIG. 6

Option 2, as shown in Figure A-2, is to imitate the QoS flow basedmechanism in NR Uu, because, as per Solution #19 in TR 23.786 [1], SA2is also proposing, at least for QoS support SL unicast, to use the PC5QoS flow based mechanism as follows [1]:

6.19.2.1.1 QoS Parameters Provision to UE and NG-RAN

The PC5 QoS parameters and PC5 QoS rule are provisioned to the UE aspart of service authorization parameters using the solution defined forKey Issue #5. The PC5 QoS rule is used to map the V2X services (e.g.PSID or ITS-AIDS of the V2X application) to the PC5 QoS flow.The PC5 QoS parameters are provisioned to the NG-RAN as part of The PC5QoS parameters retrieved by the PCF from the UDR are provided to theNG-RAN via AMF. The AMF stores such information as part of the UEcontext. For subsequent procedures (e.g., Service request, Handover),the provision of the PC5 QoS parameters via N2 will follow thedescription as per clause 6.6.2.

Particularly, in Step 0 the PC5 QoS parameters and PC5 QoS rules foreach PC5 QoS flow are provisioned to the UE in advance by serviceauthorization and provisioning procedure as above SA2 conclusions;similarly, PC5 QoS profiles for each QoS flows are also given to theeNB/ng-eNB in advance in a provisioning way. Then, when packet(s)arrive, the UE can first derive the identifier of the associated PC5 QoSflow(s) based on the PC5 QoS rules configured in Step 0, and may thenreport these PC5 QFI(s) to the gNB/ng-eNB in Step 3. At the gNB/ng-eNBside, it can derive the QoS profile(s) of these reported PC5 QFI(s)based on the provisioning from 5GC in Step 0, and thus may signal theconfigurations of the SLRB(s) associated with the PC5 QFI(s) UEreported. In Step 5, the UE in the AS establishes SLRB(s) associatedwith the PC5 QFI(s) of the packet(s) as per gNB/ng-eNB configuration,and maps available packet(s) to the SLRB(s) established.

The biggest difference from Option 1 is that, with only QFI used as inNR Uu, the specific QoS parameters of each QoS flow may not be directlyvisible in the AS of the UE/RAN, so that the gNB/ng-eNB still needs todepend on the configuration from CN to know the specific QoS profile asin Uu (though the QoS profiles are provided in a provisioning way inadvance)

Applicability:

This option, similar to Option 1, is only applicable to RRC_CONNECTEDUEs.

RAN1 #95 meeting agreed to the following (as noted in the 3GPP RAN1 #95Chairman's note):

It is supported to enable and disable SL HARQ feedback in unicast andgroupcast.FFS when HARQ feedback is enabled and disabled.

3GPP TS 36.321 states:

6.1.3.1a Sidelink BSR MAC Control Elements

Sidelink BSR and Truncated Sidelink BSR MAC control elements consist ofone Destination Index field, one LCG ID field and one correspondingBuffer Size field per reported target group.The Sidelink BSR MAC control elements are identified by MAC PDUsubheaders with LCIDs as specified in table 6.2.1-2. They have variablesizes.For each included group, the fields are defined as follows (FIGS.6.1.3.1a-1 and 6.1.3.1a-2):

-   -   Destination Index: The Destination Index field identifies the        ProSe Destination or the destination for V2X sidelink        communication. The length of this field is 4 bits. The value is        set to the index of the destination reported in        destinationInfoList for sidelink communication or is set to one        index among index(es) associated to same destination reported in        v2x-DestinationInfoList for V2X sidelink communication. If        multiple such lists are reported, the value is indexed        sequentially across all the lists in the same order as specified        in [8];    -   LCG ID: The Logical Channel Group ID field identifies the group        of logical channel(s) which buffer status is being reported. The        length of the field is 2 bits;    -   Buffer Size: The Buffer Size field identifies the total amount        of data available across all logical channels of a LCG of a        ProSe Destination after all MAC PDUs for the TTI have been        built. The amount of data is indicated in number of bytes. It        shall include all data that is available for transmission in the        RLC layer and in the PDCP layer; the definition of what data        shall be considered as available for transmission is specified        in [3] and [4] respectively. The size of the RLC and MAC headers        are not considered in the buffer size computation. The length of        this field is 6 bits. The values taken by the Buffer Size field        are shown in Table 6.1.3.1-1;    -   R: Reserved bit, set to “0”.        Buffer Sizes of LCGs are included in decreasing order of the        highest priority of the sidelink logical channel belonging to        the LCG irrespective of the value of the Destination Index        field.        [FIG. 6.1.3.1a-1 of 3GPP TS 36.321 V15.3.0, entitled “Sidelink        BSR and Truncated Sidelink BSR MAC control element for even N”,        is reproduced as FIG. 7]        [FIG. 6.1.3.1a-2 of 3GPP TS 36.321 V15.3.0, entitled “Sidelink        BSR and Truncated Sidelink BSR MAC control element for odd N”,        is reproduced as FIG. 8]

6.2.1 MAC Header for DL-SCH, UL-SCH and MCH

The MAC header is of variable size and consists of the following fields:

-   -   LCID: The Logical Channel ID field identifies the logical        channel instance of the corresponding MAC SDU or the type of the        corresponding MAC control element or padding as described in        tables 6.2.1-1, 6.2.1-2 and 6.2.1-4 for the DL-SCH, UL-SCH and        MCH respectively. There is one LCID field for each MAC SDU, MAC        control element or padding included in the MAC PDU. In addition        to that, one or two additional LCID fields are included in the        MAC PDU, when single-byte or two-byte padding is required but        cannot be achieved by padding at the end of the MAC PDU. If the        LCID field is set to “10000”, an additional octet is present in        the MAC PDU subheader containing the eLCID field and this        additional octet follows the octet containing LCID field. A UE        of Category 0 [12] except when in enhanced coverage, and        unicastFreqHoppingInd-r13 is indicated in the BR version of SI        message carrying SystemInformationBlockType2, and UE supports        frequency hopping for unicast [12] shall indicate CCCH using        LCID “01011”, a BL UE with support for frequency hopping for        unicast [12] and a UE in enhanced coverage with support for        frequency hopping for unicast [12] shall if        unicastFreqHoppingInd-r13 is indicated in the BR version of SI        message carrying SystemInformationBlockType2 indicate CCCH using        LCID “01100”, otherwise the UE shall indicate CCCH using LCID        “00000”. The LCID field size is 5 bits;    -   eLCID: The extended Logical Channel ID field identifies the        logical channel instance of the corresponding MAC SDU or the        type of the corresponding MAC control element as described in        tables 6.2.1-1a and 6.2.1-2a for the DL-SCH and UL-SCH        respectively. The size of the eLCID field is 6 bits.    -   L: The Length field indicates the length of the corresponding        MAC SDU or variable-sized MAC control element in bytes. There is        one L field per MAC PDU subheader except for the last subheader        and subheaders corresponding to fixed-sized MAC control        elements. The size of the L field is indicated by the F field        and F2 field;    -   F: The Format field indicates the size of the Length field as        indicated in table 6.2.1-3. There is one F field per MAC PDU        subheader except for the last subheader and subheaders        corresponding to fixed-sized MAC control elements and except for        when F2 is set to 1. The size of the F field is 1 bit. If the F        field is included; if the size of the MAC SDU or variable-sized        MAC control element is less than 128 bytes, the value of the F        field is set to 0, otherwise it is set to 1;    -   F2: The Format2 field indicates the size of the Length field as        indicated in table 6.2.1-3. There is one F2 field per MAC PDU        subheader. The size of the F2 field is 1 bit. If the size of the        MAC SDU or variable-sized MAC control element is larger than        32767 bytes, and if the corresponding subheader is not the last        subheader, the value of the F2 field is set to 1, otherwise it        is set to 0.    -   E: The Extension field is a flag indicating if more fields are        present in the MAC header or not. The E field is set to “1” to        indicate another set of at least R/F2/E/LCID fields. The E field        is set to “0” to indicate that either a MAC SDU, a MAC control        element or padding starts at the next byte;    -   R: Reserved bit, set to “0”.        The MAC header and subheaders are octet aligned.        [Table 6.2.1-1 of 3GPP TS 36.321 V15.3.0, entitled “Values of        LCID for DL-SCH”, is reproduced as FIG. 9]        [Table 6.2.1-1a of 3GPP TS 36.321 V15.3.0, entitled “Values of        eLCID for DL-SCH”, is reproduced as FIG. 10]        For NB-IoT only the following LCID values for DL-SCH are        applicable: CCCH, Identity of the logical channel, SC-PTM Stop        Indication, SC-MCCH/SC-MTCH, UE Contention Resolution Identity,        Timing Advance Command, DRX Command and Padding.        [Table 6.2.1-2 of 3GPP TS 36.321 V15.3.0, entitled “Values of        LCID for UL-SCH”, is reproduced as FIG. 11]

3GPP TS 38.321 states:

6.1.2 MAC PDU (DL-SCH and UL-SCH Except Transparent MAC and RandomAccess Response)

A MAC PDU consists of one or more MAC subPDUs. Each MAC subPDU consistsof one of the following:

-   -   A MAC subheader only (including padding);    -   A MAC subheader and a MAC SDU;    -   A MAC subheader and a MAC CE;    -   A MAC subheader and padding.        The MAC SDUs are of variable sizes.        Each MAC subheader corresponds to either a MAC SDU, a MAC CE, or        padding.        A MAC subheader except for fixed sized MAC CE, padding, and a        MAC SDU containing UL CCCH consists of the four header fields        R/F/LCID/L. A MAC subheader for fixed sized MAC CE, padding, and        a MAC SDU containing UL CCCH consists of the two header fields        R/LCID.        [FIG. 6.1.2-1 of 3GPP TS 38.321 V15.5.0, entitled “R/F/LCID/L        MAC subheader with 8-bit L field”, is reproduced as FIG. 12]        [FIG. 6.1.2-2 of 3GPP TS 38.321 V15.5.0, entitled “R/F/LCID/L        MAC subheader with 16-bit L field”, is reproduced as FIG. 13]        [FIG. 6.1.2-3 of 3GPP TS 38.321 V15.5.0, entitled “R/LCID MAC        subheader”, is reproduced as FIG. 14]        MAC CEs are placed together. DL MAC subPDU(s) with MAC CE(s) is        placed before any MAC subPDU with MAC SDU and MAC subPDU with        padding as depicted in FIG. 6.1.2-4. UL MAC subPDU(s) with MAC        CE(s) is placed after all the MAC subPDU(s) with MAC SDU and        before the MAC subPDU with padding in the MAC PDU as depicted in        FIG. 6.1.2-5. The size of padding can be zero.        [FIG. 6.1.2-4 of 3GPP TS 38.321 V15.5.0, entitled “Example of a        DL MAC PDU”, is reproduced as FIG. 15]        [FIG. 6.1.2-5 of 3GPP TS 38.321 V15.5.0, entitled “Example of a        UL MAC PDU”, is reproduced as FIG. 16]        [ . . . ]

6.2.1 MAC Subheader for DL-SCH and UL-SCH

The MAC subheader consists of the following fields:

-   -   LCID: The Logical Channel ID field identifies the logical        channel instance of the corresponding MAC SDU or the type of the        corresponding MAC CE or padding as described in Tables 6.2.1-1        and 6.2.1-2 for the DL-SCH and UL-SCH respectively. There is one        LCID field per MAC subheader. The LCID field size is 6 bits;    -   L: The Length field indicates the length of the corresponding        MAC SDU or variable-sized MAC CE in bytes. There is one L field        per MAC subheader except for subheaders corresponding to        fixed-sized MAC CEs, padding, and MAC SDUs containing UL CCCH.        The size of the L field is indicated by the F field;    -   F: The Format field indicates the size of the Length field.        There is one F field per MAC subheader except for subheaders        corresponding to fixed-sized MAC CEs, padding, and MAC SDUs        containing UL CCCH. The size of the F field is 1 bit. The value        0 indicates 8 bits of the Length field. The value 1 indicates 16        bits of the Length field;    -   R: Reserved bit, set to 0.        The MAC subheader is octet aligned.        [Table 6.2.1-1 of 3GPP TS 38.321 V15.5.0, entitled “Values of        LCID for DL-SCH”, is reproduced as FIG. 17]        [Table 6.2.1-2 of 3GPP TS 38.321 V15.5.0, entitled “Values of        LCID for UL-SCH”, is reproduced as FIG. 18]

According to RAN1 meeting report (as described in the 3GPP RAN1 #95Chairman's note), NR (New RAT/Radio) SL (Sidelink) will support HARQ(Hybrid Automatic Repeat Request) feedback for SL unicast and groupcast.HARQ feedback mechanism can enhance transmission reliability. If areceiving UE cannot successfully decode a packet received from atransmitting UE, the receiving UE responses a NACK of the packet to thetransmitting UE so that the transmitting UE will retransmit the packetagain.

As discussed in 3GPP R2-1900370, NW-configured SLRB (Sidelink RadioBearer) configuration for PC5 QoS (Quality of Service) flow based QoSmodel was introduced. The SLRB configuration may include SLRB ID(s), QoSflow-to-SLRB mapping, and AS configuration (e.g. PDCP (Packet DataConvergence Protocol/RLC (Radio Link Control)/LCH (Logical Channel)configurations). To request the SLRB configuration, the UE needs toprovide a PQI (QC5 5QI) for a PC5 QoS flow to the gNB. If the PQIrequires higher reliability and can tolerate longer latency, the gNB mayenable HARQ feedback on a SLRB or logical channel used to serve the PC5QoS flow. When scheduling a SL grant to the transmitting UE, the gNB mayindicate HARQ feedback resource to the transmitting UE if the SL grantis used to transmit packets that require higher reliability.

According to the LTE V2X, SL BSR is reported per LCG within adestination. If NR SL follows LTE SL, the gNB cannot know whether datain a LCG is from a SL LCH with HARQ feedback mode being enabled or notand thus cannot schedule SL grant properly. As a result, the HARQfeedback resource would be wasted if the gNB configures a SL grant to aUE while the HARQ feedback mode associated with the SL data in the UE isdisabled. Alternatives to improve HARQ feedback resource efficiencyshould be considered.

In one alternative, SL LCHs associated with different HARQ feedbackmodes may be mapped to the same LCG. This alternative is to separatebuffer sizes associated with different HARQ feedback modes under a LCGin a SL BSR (i.e. the format of a SL BSR includes at least one field ofbuffer size associated with HARQ feedback mode being enabled and onefield of buffer size associated with HARQ feedback mode being disabled).FIGS. 19A and 19B illustrate examples of SL BSR format for thisalternative.

In the first case as shown in FIG. 19A, the buffer size associated withHARQ feedback mode being enabled under a LCG and the buffer sizeassociated with HARQ feedback mode being disabled under the LCG shouldbe present simultaneously. Otherwise, the gNB cannot distinguish theHARQ feedback mode is enabled or disabled if only one buffer size ispresent under the LCG. This situation also occurs on the second case asshown in FIG. 19B. The set of Destination Index, LCG ID and Buffer Sizefor SL LCHs with HARQ feedback mode being enabled and the set ofDestination Index, LCG ID and Buffer Size for SL LCHs with HARQ feedbackmode being disabled should be present at the same time. Therefore, theabove alternative may cause signalling overhead if there is the casethat either SL LCHs with HARQ feedback enabled or SL LCHs with HARQfeedback disabled has data available for transmission. In thissituation, it is possible to include an extra field in the SL BSR forindicating the HARQ feedback mode associated with at least one buffersize field. It is also feasible to include one extra field per buffersize field. By this way, either one buffer size could be present alone.

In another alternative, the gNB can categorize LCGs (Logical ChannelGroups) into two sets of LCGs: one set is associated with HARQ feedbackbeing enabled, and the other set is associated with HARQ feedback beingdisabled. The gNB can then map a SL LCH to a LCG according to at leastthe HARQ feedback mode associated with the SL LCH. With this LCGcategorization, the gNB can know whether a buffer size in the SL BSR isassociated with a HARQ feedback mode being disabled or enabled accordingto the LCG ID. In this solution, SL LCHs associated with different HARQfeedback modes cannot be mapped to the same LCG ID. FIG. 20 illustratesexamples of SL BSR format for this alternative.

Although the second alternative can reduce signalling overhead in thefirst alternative, the second alternative may consume more LCG ID(Identity) space.

In another alternative, there are two separate SL BSRs, a first SL BSRis specific to indicate buffer status for SL LCHs with HARQ feedbackmode being enabled and a second SL BSR is specific to indicate bufferstatus for SL LCHs with HARQ feedback mode being disabled. The first SLBSR and the second SL BSR could use different LCIDs (in MAC Subheader).This alternative is illustrated in FIG. 21. However, this alternativemay consume LCID (Logical Channel Identity) space.

In another alternative, one of reserved bits in the current MAC (MediumAccess Control) subheader for a SL BSR can be used to indicate whetherHARQ feedback mode of SL LCHs of buffer status indicated in the SL BSRis enabled or not. Compared to above alternative, this alternative doesnot consume additional LCID in order to interpret different SL BSRs fordifferent HARQ feedback modes. FIG. 22 illustrates examples of MACsubheader format for SL BSR.

FIG. 23 is a flow chart 2300 according to one exemplary embodiment fromthe perspective of a UE to handle a sidelink buffer status report (SLBSR). In step 2305, the UE transmits a SL BSR to a network node, whereina format of the SL BSR includes at least one field of buffer sizeassociated with HARQ feedback enabled and one field of buffer sizeassociated with HARQ feedback disabled. In step 2310, the UE receives asidelink grant from the network node. In step 2315, the UE selects datafrom a logical channel for transmission according to a HARQ feedbackmode of the logical channel and whether the sidelink grant is associatedwith a HARQ feedback resource or not.

In one embodiment, the data from the logical channel associated withHARQ feedback enabled could be selected if the sidelink grant isassociated with a HARQ feedback resource. Alternatively, the data fromthe logical channel associated with HARQ feedback disabled could beselected if the sidelink grant is not associated with a HARQ feedbackresource.

In one embodiment, the UE could receive a SLRB configuration from thenetwork node, wherein the SLRB configuration configures the UE with afirst logical channel associated with HARQ feedback enabled and a secondlogical channel associated with HARQ feedback disabled.

In one embodiment, the network node could be a base station (e.g. gNB).

Referring back to FIGS. 3 and 4, in one exemplary embodiment of a UE,the device 300 includes a program code 312 stored in the memory 310. TheCPU 308 could execute program code 312 to enable the UE (i) to transmita SL BSR to a network node, wherein a format of the SL BSR includes atleast one field of buffer size associated with HARQ feedback enabled andone field of buffer size associated with HARQ feedback disabled, (ii) toreceive a sidelink grant from the network node, and (iii) to select datafrom a logical channel for transmission according to a HARQ feedbackmode of the logical channel and whether the sidelink grant is associatedwith a HARQ feedback resource or not. Furthermore, the CPU 308 canexecute the program code 312 to perform all of the above-describedactions and steps or others described herein.

FIG. 24 is a flow chart 2400 according to one exemplary embodiment fromthe perspective of a network node to handle a SL BSR. In step 2405, thenetwork node receives a SL BSR from a UE, wherein a format of the SL BSRincludes at least one field of buffer size associated with HARQ feedbackenabled and one field of buffer size associated with HARQ feedbackdisabled. In step 2410, the network node transmits a sidelink grant tothe UE according to the SL BSR.

In one embodiment, whether the sidelink grant is associated with a HARQfeedback resource or not depends on content in the SL BSR. The networknode could transmits a SLRB configuration to the UE, wherein the SLRBconfiguration configures the UE with a first logical channel associatedwith HARQ feedback enabled and a second logical channel associated withHARQ feedback disabled. The network node could also transmit a firstsidelink grant associated with the HARQ feedback resource to the UE ifthe buffer size associated with HARQ feedback enabled in the SL BSR isnot empty. Furthermore, the network node could transmit a secondsidelink grant not associated with the HARQ feedback resource to the UEif the buffer size associated with HARQ feedback disabled in the SL BSRis not empty.

In one embodiment, the SLRB configuration may configure the UE to mapthe first logical channel and the second logical channel to a LCG. Thefield of buffer size associated with HARQ feedback enabled couldidentify total amount of data available across all logical channelsassociated with HARQ feedback enabled of the LCG, and all logicalchannels include the first logical channel and do not include the secondlogical channel. The field of buffer size associated with HARQ feedbackdisabled could also identify the total amount of data available acrossall logical channels associated with HARQ feedback disabled of the LCG,and all logical channels include the second logical channel and do notinclude the first logical channel.

In one embodiment, the sidelink grant may include frequency domaininformation of the HARQ feedback resource if the sidelink grant isassociated with the HARQ feedback resource. The sidelink grant may alsoinclude time domain information of the HARQ feedback resource if thesidelink grant is associated with the HARQ feedback resource.

Alternatively, the sidelink grant may not include frequency domaininformation of the HARQ feedback resource if the sidelink grant is notassociated with the HARQ feedback resource. Furthermore, the sidelinkgrant may not include time domain information of the HARQ feedbackresource if the sidelink grant is not associated with the HARQ feedbackresource.

In one embodiment, the sidelink transmission could further include datafrom a logical channel with HARQ feedback disabled if the sidelink grantis associated with the HARQ feedback resource. The sidelink transmissionmay not include data from a logical channel with HARQ feedback enabledif the sidelink grant is not associated with the HARQ feedback resource.

In one embodiment, the network node could be a base station (e.g. gNB).There may be a field in the SL BSR used to indicate a HARQ feedback modeof at least one field of buffer size.

Referring back to FIGS. 3 and 4, in one exemplary embodiment of anetwork node, the device 300 includes a program code 312 stored in thememory 310. The CPU 308 could execute program code 312 to enable thenetwork node (i) to receive a SL BSR from a UE, wherein a format of theSL BSR includes at least one field of buffer size associated with HARQfeedback enabled and one field of buffer size associated with HARQfeedback disabled, and (ii) to transmit a sidelink grant to the UEaccording to the SL BSR. Furthermore, the CPU 308 can execute theprogram code 312 to perform all of the above-described actions and stepsor others described herein.

FIG. 25 is a flow chart 2500 according to one exemplary embodiment fromthe perspective of a network node to handle a SL BSR. In step 2505, thenetwork node configures a sidelink logical channel (SL LCH) to a UE,wherein the SL LCH is configured with a HARQ feedback mode and mapped toa LCG according to the HARQ feedback mode, and there are at least twosets of LCGs: one set is associated with HARQ feedback enabled and theother set is associated with HARQ feedback disabled. In step 2510, thenetwork node receives a SL BSR from the UE, wherein the SL BSR includesat least one LCG and there is a buffer size per LCG. In step 2515, thenetwork node transmits a sidelink grant to the UE according to the SLBSR.

In one embodiment, whether the sidelink grant is associated with a HARQfeedback resource or not depends on content in the SL BSR.

In one embodiment, the network node could transmit a SLRB configurationto the UE, wherein the SLRB configuration configures the UE with a firstlogical channel associated with HARQ feedback enabled and a secondlogical channel associated with HARQ feedback disabled. The SLRBconfiguration may configure the UE to map the first logical channel to afirst LCG and map the second logical channel to a second LCG.

In one embodiment, the network node could transmit a first sidelinkgrant associated with the HARQ feedback resource to the UE if the buffersize of the first LCG in the SL BSR is not empty. The network node couldalso transmit a second sidelink grant not associated with the HARQfeedback resource to the UE if the buffer size of the second LCG in theSL BSR is not empty.

In one embodiment, the field of buffer size of the first LCG mayidentify the total amount of data available across all logical channelsassociated with HARQ feedback enabled of the first LCG, and the alllogical channels include the first logical channel and do not includethe second logical channel. Furthermore, the field of buffer size of thesecond LCG may identify the total amount of data available across alllogical channels associated with HARQ feedback disabled of the secondLCG, and the all logical channels include the second logical channel anddo not include the first logical channel.

In one embodiment, the sidelink grant may include frequency domaininformation of the HARQ feedback resource if the sidelink grant isassociated with the HARQ feedback resource. The sidelink grant may alsoinclude time domain information of the HARQ feedback resource if thesidelink grant is associated with the HARQ feedback resource.

Alternatively, the sidelink grant may not include frequency domaininformation of the HARQ feedback resource if the sidelink grant is notassociated with the HARQ feedback resource. Furthermore, the sidelinkgrant may not include time domain information of the HARQ feedbackresource if the sidelink grant is not associated with the HARQ feedbackresource.

In one embodiment, the sidelink transmission may further include datafrom a logical channel with HARQ feedback disabled if the sidelink grantis associated with the HARQ feedback resource. In addition, the sidelinktransmission may not include data from a logical channel with HARQfeedback enabled if the sidelink grant is not associated with the HARQfeedback resource.

In one embodiment, the network node could be a base station (e.g. gNB).

Referring back to FIGS. 3 and 4, in one exemplary embodiment of a firstUE, the device 300 includes a program code 312 stored in the memory 310.The CPU 308 could execute program code 312 to enable the first UE (i) toconfigure a SL LCH to a UE, wherein the SL LCH is configured with a HARQfeedback mode and mapped to a LCG according to the HARQ feedback mode,and there are at least two sets of LCGs: one set is associated with HARQfeedback enabled and the other set is associated with HARQ feedbackdisabled, (ii) to receive a SL BSR from the UE, wherein the SL BSRincludes at least one LCG and there is a buffer size per LCG, and (iii)to transmit a sidelink grant to the UE according to the SL BSR.Furthermore, the CPU 308 can execute the program code 312 to perform allof the above-described actions and steps or others described herein.

FIG. 26 is a flow chart 2600 according to one exemplary embodiment fromthe perspective of a UE to handle a SL BSR. In step 2605, the UEtransmits a MAC PDU to a network node, wherein the MAC PDU includes atleast a first subheader and a first SL BSR associated with a first HARQfeedback mode, and a field of the first subheader indicates the firstHARQ feedback mode. In step 2610, the UE receives a sidelink grant fromthe network node. In step 2615, the UE selects data from a logicalchannel for transmission according to a HARQ feedback mode of thelogical channel and whether the sidelink grant is associated with a HARQfeedback resource or not.

In one embodiment, the data from the logical channel associated withHARQ feedback enabled may be selected if the sidelink grant isassociated with a HARQ feedback resource. Alternatively, the data fromthe logical channel associated with HARQ feedback disabled may beselected if the sidelink grant is not associated with a HARQ feedbackresource.

In one embodiment, the UE could receive a SLRB configuration from thenetwork node, wherein the SLRB configuration configures the UE with afirst logical channel associated with HARQ feedback enabled and a secondlogical channel associated with HARQ feedback disabled. The MAC PDUcould further include a second subheader and a second SL BSR associatedwith a second HARQ feedback mode which is different from the first HARQfeedback mode, and a field of the second subheader indicates the secondHARQ feedback mode.

Referring back to FIGS. 3 and 4, in one exemplary embodiment of a UE,the device 300 includes a program code 312 stored in the memory 310. TheCPU 308 could execute program code 312 to enable the UE (i) to transmita MAC PDU to a network node, wherein the MAC PDU includes at least afirst subheader and a first SL BSR associated with a first HARQ feedbackmode, and a field of the first subheader indicates the first HARQfeedback mode, (ii) to receive a sidelink grant from the network node,and (iii) to select data from a logical channel for transmissionaccording to a HARQ feedback mode of the logical channel and whether thesidelink grant is associated with a HARQ feedback resource or not.Furthermore, the CPU 308 can execute the program code 312 to perform allof the above-described actions and steps or others described herein.

FIG. 27 is a flow chart 2700 according to one exemplary embodiment fromthe perspective of a network node to handle a SL BSR. In step 2705, thenetwork node receives a MAC PDU from a UE, wherein the MAC PDU includesat least a first subheader and a first SL BSR associated with a firstHARQ feedback mode, and a field of the first subheader indicates thefirst HARQ feedback mode. In step 2710, the network node transmits asidelink grant to the UE according to the first SL BSR.

In one embodiment, whether the sidelink grant is associated with a HARQfeedback resource or not depends on content in the first SL BSR. Thenetwork node could transmit a SLRB configuration to the UE, wherein theSLRB configuration configures the UE with a first logical channelassociated with HARQ feedback enabled and a second logical channelassociated with HARQ feedback disabled. The MAC PDU could furtherinclude a second subheader and a second SL BSR associated with a secondHARQ feedback mode which is different from the first HARQ feedback mode,and a field of the second subheader indicates the second HARQ feedbackmode.

In one embodiment, the network node could transmit a first sidelinkgrant associated with the HARQ feedback resource to the UE if the (firstor second) HARQ feedback mode is enabled. The network node could alsotransmit a second sidelink grant not associated with the HARQ feedbackresource to the UE if the (first or second) HARQ feedback mode isdisabled.

In one embodiment, the field of the first or second subheader couldindicate the first or second HARQ feedback mode is enabled if the firstor second SL BSR includes buffer size(s) of logical channel(s)associated with HARQ feedback enabled, and the logical channel(s)include the first logical channel and do not include the second logicalchannel. Alternatively, the field of the first or second subheader couldindicate the first or second HARQ feedback mode is disabled if the firstor second SL BSR includes buffer size(s) of logical channel(s)associated with HARQ feedback disabled, and the logical channel(s)include the second logical channel and do not include the first logicalchannel.

In one embodiment, the field of the first or second subheader could beused to indicate the HARQ feedback mode is a LCID field. The field ofthe first or second subheader could also be used to indicate the HARQfeedback mode is a one-bit field.

In one embodiment, the (first) sidelink grant could include frequencydomain information of the HARQ feedback resource if the (first) sidelinkgrant is associated with the HARQ feedback resource. The (first)sidelink grant could also include time domain information of the HARQfeedback resource if the (first) sidelink grant is associated with theHARQ feedback resource.

In one embodiment, the (second) sidelink grant may not include frequencydomain information of the HARQ feedback resource if the (second)sidelink grant is not associated with the HARQ feedback resource.Furthermore, the (second) sidelink grant may not include time domaininformation of the HARQ feedback resource if the (second) sidelink grantis not associated with the HARQ feedback resource.

In one embodiment, the sidelink transmission could further include datafrom a logical channel with HARQ feedback disabled if the (first)sidelink grant is associated with the HARQ feedback resource. Thesidelink transmission may not include data from a logical channel withHARQ feedback enabled if the (second) sidelink grant is not associatedwith the HARQ feedback resource.

In one embodiment, the network node could be a base station (e.g. gNB).

Referring back to FIGS. 3 and 4, in one exemplary embodiment of anetwork node, the device 300 includes a program code 312 stored in thememory 310. The CPU 308 could execute program code 312 to enable thenetwork node (i) to receive a MAC PDU from a UE, wherein the MAC PDUincludes at least a first subheader and a first SL BSR associated with afirst HARQ feedback mode, and a field of the first subheader indicatesthe first HARQ feedback mode, and (ii) to transmit a sidelink grant tothe UE according to the first SL BSR. Furthermore, the CPU 308 canexecute the program code 312 to perform all of the above-describedactions and steps or others described herein.

Various aspects of the disclosure have been described above. It shouldbe apparent that the teachings herein could be embodied in a widevariety of forms and that any specific structure, function, or bothbeing disclosed herein is merely representative. Based on the teachingsherein one skilled in the art should appreciate that an aspect disclosedherein could be implemented independently of any other aspects and thattwo or more of these aspects could be combined in various ways. Forexample, an apparatus could be implemented or a method could bepracticed using any number of the aspects set forth herein. In addition,such an apparatus could be implemented or such a method could bepracticed using other structure, functionality, or structure andfunctionality in addition to or other than one or more of the aspectsset forth herein. As an example of some of the above concepts, in someaspects concurrent channels could be established based on pulserepetition frequencies. In some aspects concurrent channels could beestablished based on pulse position or offsets. In some aspectsconcurrent channels could be established based on time hoppingsequences. In some aspects concurrent channels could be establishedbased on pulse repetition frequencies, pulse positions or offsets, andtime hopping sequences.

Those of skill in the art would understand that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

Those of skill would further appreciate that the various illustrativelogical blocks, modules, processors, means, circuits, and algorithmsteps described in connection with the aspects disclosed herein may beimplemented as electronic hardware (e.g., a digital implementation, ananalog implementation, or a combination of the two, which may bedesigned using source coding or some other technique), various forms ofprogram or design code incorporating instructions (which may be referredto herein, for convenience, as “software” or a “software module”), orcombinations of both. To clearly illustrate this interchangeability ofhardware and software, various illustrative components, blocks, modules,circuits, and steps have been described above generally in terms oftheir functionality. Whether such functionality is implemented ashardware or software depends upon the particular application and designconstraints imposed on the overall system. Skilled artisans mayimplement the described functionality in varying ways for eachparticular application, but such implementation decisions should not beinterpreted as causing a departure from the scope of the presentdisclosure.

In addition, the various illustrative logical blocks, modules, andcircuits described in connection with the aspects disclosed herein maybe implemented within or performed by an integrated circuit (“IC”), anaccess terminal, or an access point. The IC may comprise a generalpurpose processor, a digital signal processor (DSP), an applicationspecific integrated circuit (ASIC), a field programmable gate array(FPGA) or other programmable logic device, discrete gate or transistorlogic, discrete hardware components, electrical components, opticalcomponents, mechanical components, or any combination thereof designedto perform the functions described herein, and may execute codes orinstructions that reside within the IC, outside of the IC, or both. Ageneral purpose processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

It is understood that any specific order or hierarchy of steps in anydisclosed process is an example of a sample approach. Based upon designpreferences, it is understood that the specific order or hierarchy ofsteps in the processes may be rearranged while remaining within thescope of the present disclosure. The accompanying method claims presentelements of the various steps in a sample order, and are not meant to belimited to the specific order or hierarchy presented.

The steps of a method or algorithm described in connection with theaspects disclosed herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module (e.g., including executable instructions and relateddata) and other data may reside in a data memory such as RAM memory,flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a harddisk, a removable disk, a CD-ROM, or any other form of computer-readablestorage medium known in the art. A sample storage medium may be coupledto a machine such as, for example, a computer/processor (which may bereferred to herein, for convenience, as a “processor”) such theprocessor can read information (e.g., code) from and write informationto the storage medium. A sample storage medium may be integral to theprocessor. The processor and the storage medium may reside in an ASIC.The ASIC may reside in user equipment. In the alternative, the processorand the storage medium may reside as discrete components in userequipment. Moreover, in some aspects any suitable computer-programproduct may comprise a computer-readable medium comprising codesrelating to one or more of the aspects of the disclosure. In someaspects a computer program product may comprise packaging materials.

While the invention has been described in connection with variousaspects, it will be understood that the invention is capable of furthermodifications. This application is intended to cover any variations,uses or adaptation of the invention following, in general, theprinciples of the invention, and including such departures from thepresent disclosure as come within the known and customary practicewithin the art to which the invention pertains.

1. A method for a UE to handle a sidelink buffer status report (SL BSR),comprising: transmitting a SL BSR to a network node, wherein a format ofthe SL BSR includes at least one field of buffer size associated withHARQ (Hybrid Automatic Repeat Request) feedback enabled and one field ofbuffer size associated with HARQ feedback disabled; receiving a sidelinkgrant from the network node; and selecting data from a logical channelfor transmission according to a HARQ feedback mode of the logicalchannel and whether the sidelink grant is associated with a HARQfeedback resource or not.
 2. The method of claim 1, wherein the datafrom the logical channel associated with HARQ feedback enabled isselected if the sidelink grant is associated with a HARQ feedbackresource.
 3. The method of claim 1, wherein the data from the logicalchannel associated with HARQ feedback disabled is selected if thesidelink grant is not associated with a HARQ feedback resource.
 4. Themethod of claim 1, further comprising: receiving a SLRB configurationfrom the network node, wherein the SLRB configuration configures the UEwith a first logical channel associated with HARQ feedback enabled and asecond logical channel associated with HARQ feedback disabled.
 5. Themethod of claim 1, wherein the network node is a base station.
 6. Amethod for a network node to handle a sidelink buffer status report (SLBSR), comprising: receiving a SL BSR from a UE (User Equipment), whereina format of the SL BSR includes at least one field of buffer sizeassociated with HARQ (Hybrid Automatic Repeat Request) feedback enabledand one field of buffer size associated with HARQ feedback disabled; andtransmitting a sidelink grant to the UE according to the SL BSR.
 7. Themethod of claim 6, wherein whether the sidelink grant is associated witha HARQ feedback resource or not depends on content in the SL BSR.
 8. Themethod of claim 6, further comprising: transmitting a SLRB configurationto the UE, wherein the SLRB configuration configures the UE with a firstlogical channel associated with HARQ feedback enabled and a secondlogical channel associated with HARQ feedback disabled.
 9. The method ofclaim 6, further comprising: transmitting a first sidelink grantassociated with the HARQ feedback resource to the UE if the buffer sizeassociated with HARQ feedback enabled in the SL BSR is not empty. 10.The method of claim 6, further comprising: transmitting a secondsidelink grant not associated with the HARQ feedback resource to the UEif the buffer size associated with HARQ feedback disabled in the SL BSRis not empty.
 11. The method of claim 6, wherein the network node is abase station.
 12. A method for a network node to handle a sidelinkbuffer status report (SL BSR), comprising: configuring a sidelinklogical channel (SL LCH) to a UE, wherein the SL LCH is configured witha HARQ (Hybrid Automatic Repeat Request) feedback mode and mapped to aLCG (Logical Channel Group) according to the HARQ feedback mode, andthere are at least two sets of LCGs: one set is associated with HARQfeedback enabled and the other set is associated with HARQ feedbackdisabled; receiving a SL BSR from the UE, wherein the SL BSR includes atleast one LCG and there is a buffer size per LCG; and transmitting asidelink grant to the UE according to the SL BSR.
 13. The method ofclaim 12, wherein whether the sidelink grant is associated with a HARQfeedback resource or not depends on content in the SL BSR.
 14. Themethod of claim 12, further comprising: transmitting a SLRBconfiguration to the UE, wherein the SLRB configuration configures theUE with a first logical channel associated with HARQ feedback enabledand a second logical channel associated with HARQ feedback disabled, andwherein the SLRB configuration configures the UE to map the firstlogical channel to a first LCG and map the second logical channel to asecond LCG.
 15. The method of claim 12, further comprising: transmittinga first sidelink grant associated with the HARQ feedback resource to theUE if the buffer size associated with HARQ feedback enabled in the SLBSR is not empty.
 16. The method of claim 12, further comprising:transmitting a second sidelink grant not associated with the HARQfeedback resource to the UE if the buffer size associated with HARQfeedback disabled in the SL BSR is not empty.
 17. The method of claim12, wherein the network node is a base station.